It will be recognized that a solenoid assembly can be used in various actuator assemblies for actuation of a certain component and not limited to motor vehicles or internal combustion engines. One use for an actuator assembly having a solenoid involves a vehicle automatic transmission. Electromechanical solenoid operated control valves are widely used in the area of electronically controlled automatic transmissions. Two general types of such control valves include pulse width modulated (PWM) and linear control valves. Both types are responsive to a control quantity, typically time varying voltage or current, to control line pressure, clutch chamber pressure or pilot pressure in a spool valve. It is generally understood that PWM valves have an armature which strokes between first and second positions substantially in frequency correspondence with a time varying voltage signal while a linear control valve has an armature which assumes an equilibrium position in accordance with the electromagnetic force generated by the average current through the solenoid coil and internal bias spring and hydraulic forces.
Low leak solenoids are used in automatic transmissions to get smooth shifting with the advantage of reducing mechanical load of the oil pump. A solenoid is used to provide pressure control or flow output proportional to the pulse width modulated voltage or current level.
Two primary actuator configurations exist to provide pressure control or flow output proportional to an electrical control signal. A proseal configuration allows inlet pressure to create a hydraulic force that biases a ball or poppet against a valve seat to seal the valve seat, wherein increased inlet pressure aids in seating the ball against the valve seat. In a contraseal configuration, inlet pressure acts to break a seal between a poppet and valve seat, wherein the pressure at which the seal is broken is limited to a high spring preload that acts axially against the poppet to counter the inlet pressure and maintain a seal between the poppet and valve seat.
Both of the above configurations require a magnetic package that generates a magnetic flux strong enough to overcome the spring preloads associated with known contraseal and proseal configurations. Furthermore, high mechanical forces created as result of overcoming the high spring preloads increase wear between components. Moreover, higher mechanical forces cause misalignment between components because larger axial forces project into larger radial forces. For these above reasons, a proseal configuration is the preferred design choice.
In one contraseal configuration illustrated in FIG. 1, multiple components are assembled together that can affect dimensional stack up and is a significant source of part-to-part variation resulting in variation of the stroke of the valve. Dimensional stack up also poses potential alignment issues.
As such, the present invention has recognized these prior art drawbacks, and has provided the below-disclosed solutions to one or more of the prior art deficiencies.